The present invention relates to telecommunications systems, and more particularly to a system for converting TDM-based digital cross-connect system matrix data containing frame relay data to and from ATM data.
Digital cross-connect systems (DCS) constitute switching/multiplex equipment that permit per-channel DS0 electronic cross-connection from one T1 transmission facilities to another, directly from the constituent DS1 signals. A basic multiplexing method used in telecommunications digital cross-connect systems is time division multiplexing (TDM). In TDM, a transmission facility is shared in time rather than frequency. In a TDM system, a frame is a sequence of time slots, each containing a sample from one of the channels served by the multiplex system. The frame is repeated at the sampling rate, and each channel occupies the same sequence position in successive frames. To permit higher levels of multiplexing concentration, a multi-level TDM digital signal hierarchy has been developed.
The DS1 level in the hierarchy corresponds to the 1.544 Mbps TDM signal. The DS0 level refers to the individual time slot digital signals at channel rates of 64 kbps. Four DS1 signals comprise a DS2 level signal containing 96 DS0 channels. A DS3 level signal results from the digital multiplexing of seven DS2 signals. The DS designation refers to the signal level hierarchy and is independent of the type of carrier facility.
Frame relay is a high-speed switching technology utilized in a form of packet switching. The packets are in the form of xe2x80x9cframesxe2x80x9d which are variable in length. A frame relay network can accommodate data packets of various sizes associated with virtually any native data protocol.
Asynchronous transfer mode (ATM) is a high speed transmission technology utilizing a high bandwidth, low-delay, connection-oriented, packet-like switching and multiplexing technique. ATM allocates bandwidth on demand, making it suitable for high speed connection of voice, data, and video services.
In telecommunications systems, digital cross-connect systems are required to convert TDM based matrix data containing frame relay data to and from DS3 ATM data. Typically, equipment is separate from the cross-connect system that performs TDM-frame relay and frame-relay ATM conversion. Such equipment requires additional rack and bay locations from the digital cross-connect system as well as additional interfaces.
To improve the efficiency in telecommunications systems as well as to provide economical systems it is desirable to include additional functions within a digital cross-connect system. A need has thus arisen for a system to extract frame relay data from TDM data at a narrow band cross-connect switching matrix to perform conversion of the frame relay data to/from a DS3 ATM interface and perform adaption processing between the frame relay and ATM domains in a narrow band cross-connect system.
The present invention provides for a high density frame relay circuit pack to be installed in a subsystem of a digital cross-connect system. The frame relay circuit pack converts TDM based data containing frame relay data to/from a DS3 ATM physical interface and performs adaption processing between the frame relay and ATM domains. The frame relay circuit pack converts DS0 channelized and DS1 unchannelized frame relay traffic to DS3 ATM data in the outbound direction and converts DS3 ATM traffic to DS0 channelized or DS1 unchannelized frame relay data in the inbound direction.